Photographic material with a stabilizer antifoggant bidentate compound

ABSTRACT

PHOTOGRAPHIC MATERIALS ARE PROVIDED WHICH COMPRISE IN A LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER OR IN A WATERPERMEABLE LAYER ADJACENT THERETO A COMPOUND OF THE FORMULA:   X-Q-A-C&lt;(=N-Z-NH-)   WHEREIN: Z REPRESENTS THE ATOMS NECESSARY TO CLOSE A HETEROCYCLE, Q STANDS FOR SULPHUR OR SELENIUM, A STANDS FOR ALKYLENE WHICH MAY BE INTERRUPTED BY ONE OR MORE HETERO ATOMS, S-ALKYLENE WHICH MAY BE INTERRUPTED BY ONE OR MORE HETERO ATOMS, OR ARYLENE, X STANDS FOR ALKYL, ALKENYL OR ARYL, OR A AND X TOGETHER REPRESENT THE ATOMS NECESSARY TO COMPLETE A SATURATED HETEROCYCLE, THE SAID COMPOUND COMPRISING DIRECTLY OR INDIRECTLY LINKED TO THE GROUP Z AND/OR X A -COOM OR SO3M GROUP WHEREIN M IS HYDROGEN, AMMONIUM, A METAL ATOM OR ORGANIC AMMONIUM. THESE MATERIALS HAVE REDUCED FOGGING TENDENCY, EVEN UNDER CONDITIONS OF HIGH HUMIDITY AND HEAT, AND THEIR SENSITIVITY IS SUBSTANTIALLY UNAFFECTED BY THE PRESENCE OF THE AFORESAID COMPOUND.

US. Cl. 96-109 7 Claims ABSTRACT OF THE DISCLOSURE Photographic materials are provided which comprise in a light-sensitive silver halide emulsion layer or in a waterpermeable layer adjacent thereto a compound of the formula:

wherein:

Z represents the atoms necessary to close a heterocycle,

Q stands for sulphur or selenium,

A stands for alkylene which may be interrupted by one or more hetero atoms, S-alkylene which may be interrupted by one or more hetero atoms, or arylene,

X stands for alkyl, alkenyl or aryl, or

A and X together represent the atoms necessary to complete a saturated heterocycle,

the said compound comprising directly or indirectly linked to the group Z and/or X a -COOM or --SO M group wherein M is hydrogen, ammonium, a metal atom or organic ammonium. These materials have reduced fogging tendency, even under conditions of high humidity and heat, and their sensitivity is substantially unafiected by the presence of the aforesaid compound.

This invention relates to improved photographic materials comprising light-sensitive silver halide emulsions, more particularly to photographic materials having less tendency to fog formation and still possessing the same light-sensitivity.

It is well known that light-sensitive silver halide materials comprising gelatin silver halide emulsion layers are subject to fogging. Fogging in general and chemical fogging in particular may be defined as the formation of a uniform deposit of silver on development which is dependent on a whole series of circumstances and factors namely on the nature of the emulsions, on their age, on the conditions under which they have been stored, on the development conditions, etc. For particular development conditions the fog tends to be greater as the time of storage and the temperature and relative humidity of the atmosphere in which the emulsions are stored are increased. Consequently it is known to carry out accelerated tests called incubation tests on the stability of photographic emulsions by storing them at elevated temperature and humidity and then determining their sensitometric characteristics.

Addenda to the photographic material known as stabilizers or antifoggants protect the light-sensitive silver halide emulsions against formation and growth of fog particularly in high sensitive emulsions and in emulsions which are to be stored under conditions of high temperature and humidity as is for instance the case in tropical countries.

9 United States Patent 3,667,957. Patented June 6, 1972 In accordance with the invention it has been found that bidentate compounds corresponding to the following general formula:

wherein:

Z represents the atoms necessary to complete a heterocycle including a substituted heterocycle and a heterocycle with fused aromatic ring e.g. the atoms necessary to complete an imidazole nucleus, a benzimidazole nucleus, a naphthimidazole nucleus, a triazole nucleus, a tetrazole nucleus, etc.

Q stands for a sulphur atom or selenium atom;

A stands for alkylene such as methylene, ethylene, trimethylene, etc. including substituted alkylene and alkylene interrupted by one or more hetero atoms, -S-alkylene including substituted S-alkylene and S-alkylene interrupted by one or more hetero atoms or arylene including substituted arylene,

X stands for alkyl including substituted alkyl, alkenyl including substituted alkenyl or aryl including substituted aryl, or

A and X together represent the atoms necessary to complete a saturated heterocycle including a substituted heterocycle, and

wherein a water-solubilizing group, more particularly a -COOM or SO M group, with M=hydrogen, ammonium, a metal atom, an organic amine, etc. is linked directly or indirectly to the grouping Z and/or X,

are particularly good stabilizers and antifoggants for photographic light-sensitive silver halide emulsions without causing an objectionable desensitization of the lightsensitive material.

The compounds corresponding to the above general formula are bidentate ligands forming complexes with silver i.e. they contain two coordinating atoms for silver, the nitrogen atom of the NH- moiety of the heterocycle being one of the coordinating atoms and the Q-atom i.e. sulphur or selenium being the other coordinating atom. As will be illustrated by comparative tests in the examples hereinafter, the said NH moiety and the Q-atoms, their relative positions in the molecule and also the presence of the water-solubilizing group(s) are essential features of the compounds according to the invention for use as stabilizers. Indeed, compounds corresponding to the above general formula but containing no water-solubilizing groups possess not at all interesting properties as stabilizers. Further, compounds of similar structure but containing a substituent on the --NH-- moiety of the heterocycle have a less good stabilizing effect. Moreover, closely similar compounds differing from the compounds of the invention only in that the group QX is directly linked to the heterocycle i.e. compounds wherein A is a chemical bond have no stabilizing action at all, owing to the fact that in that case the sulphur or selenium atom loses its coordinating action with regard to silver because when directly linked to the heterocycle the unshared electron pairs on the sulphur or selenium atom (Q) are interacting with the delocalized or spread 1r-Cl6Ctl'OnS of the strongly electron withdrawing heterocycle i.e. they are held in common by the whole of the conjugate system. This is not the case with the compounds according to the present invention since the intervening group A prevents interaction of the unshared electron pairs of the Q atom with the 1r-electrons of the nucleus i.e. conjugation does not extend as far as the Q atom.

The compounds having the structures below are representative of those falling within the scope of the above general formula:

The above specific compounds can be prepared as illustrated by the following preparations:

Preparation lzCompound l 12.7 g. of 3,4-diaminobenzenesulphonic acid and 8 g.

of B-methylthiopropionic acid were refluxed for 12 hours in ml. of 6 N hydrochloric acid. The solution was filtered over decolourising carbon, the hydrochloric acid was evaporated and the residue was recrystallized from water. 8 g. of 2-(2-methylthioethyl) -5(6)sulphobenzimidazole were obtained.

Preparation 3 :Compound 3 94 g. of 3,4-diaminobenzenesulphonic acid and 67 g. of 'y-methylthiobutyric acid were refluxed for 12 hours in 750 ml. of 6 N hydrochloric acid. The solution was filtered over decolourising carbon, the hydrochloric acid was evaporated and the residue 'was recrystallized from water. 25 g. of 2-(3-methylthiopropyl-5(6)-sulphobenzimidazole were obtained.

Preparation 4:Compound 4 56.8 g. of 3,4-diaminobenzoic acid hydrochloride and 31.8 g. of methylthioacetic acid were refluxed for 8 hours in 420 ml. of 6 N hydrochloric acid. Upon cooling the crude benzimidazole compound crystallized whereupon it was recrystallized from aqueous methanol. 50 g. of 2 methylthiomethyl-S(6)-carboxybenzi.midazole hydrochloride were obtained.

Preparation 5 :Compound 5 To a solution of 20 g. of 2-mercaptomethylbenzimidazole prepared according to E. S. Milner et al., J1. Chem. Soc. 1964, 4151 and 6.5 g. of sodium methylate in 300 ml. of methanol, 15 g. of propanesultone were added whereupon the whole was refluxed for 2 hours. The solution was filtered over decolourising carbon, the methanol was removed by evaporation, and the residue was taken up in alkali. Then the solution was filtered and acidified whereupon the solid product formed was recrystallized from water. 15 g. of 2-(3-sulphopropylthiomethyl)benzimidazole were obtained.

Preparation 6 Compound 6 Preparation 7 :Compound 7 To a solution of 25 g. of 2-mercaptomethylbenzimidazole in 150 ml. of 1 N sodium hydroxide was added at 50 C. a solution of 17.4 g. of sodium chloroacetate in 100 ml. of water. After having been stirred for 30 min. the solution was acidified with acetic acid. The precipitate formed 'Was recrystallized from aqueous ethanol. 16 g. of 2-carboxymethylthiomethylbenzimidazole were obtained.

Preparation 8 :Compound 8 To a solution of 8.2 g. of 2-mercaptomethylbenzimidazole and 2.7 g. of sodium methylate in 100 ml. of methanol, 6.8 g. of butanesultone were added whereupon the whole was refluxed for 2 hours. The solution was filtered over decolourising carbon, the methanol was removed by evaporation and the residue was taken upon in alkali. The solution was filtered and acidified. By crystallisation from water 4 g. of 2-(4-sulphobutylthiomethyl) benzimidazole were obtained.

Preparation 92Compound 9 To a solution of 8.2 g. of 2-mercaptomethylbenzimidazole and 2.7 g. of sodium methyl-ate in 100 ml. of methanol were added 8.2 g. of 1,1,3-trimethylpropanesultone whereupon the whole was refluxed for 2 hours. The solution was filtered over decolourising carbon, the methanol was removed by evaporation and the residue was taken up in alkali. The solution formed was filtered and acidified. By crystallisation from water 3 g. of 2-(1,3- dimethyl-3-sulphobutylthiomethyl)benzimidazole were obtained.

Preparation 10:Compound 10 (a) 188 g. of 3,4-diaminobenzenesulphonic acid and 115 g. of mercaptoacetic acid were refluxed for 6 hours in 500 ml. of 6 N hydrochloric acid. The solution was filtered over decolourising carbon, the hydrochloric acid removed by evaporation and the residue taken up in alkali. Then the solution was filtered and acidified whereupon the solid formed was recrystallized from water. 113 g. of 2-mercaptomethyl-5(6)-sulphobenzimidazole were obtained.

(b) To a solution of 12.2 g. of 2-mercaptomethyl-5(6)- sulphobenzimidazole in ml of 1 N sodium hydroxide, 12.2 g. of propanesultone were added slowly at room temperature with stirring. The resulting solution was kept for 15 hours at room temperature. The solid obtained by quenching the aqueous solution in 1 litre of ethanol was dissolved in 2 litres of water whereupon the solution was conducted over beads of insoluble sulphonated polystyrene as cation exchanger. The eluate was evaporated and the residue washed with acetonitrile. 17 g. of 2'-(3 sulphopropylthiomethyD-S(6)-sulphobenzimidazole were obtained.

Preparation 11:Compound 11 (a) 21.6 g. of o-phenylenediamine and 23.8 g. of bis(3- carboxypropyl)disulfide were refluxed for 24 hours in 200 ml. of 6 N hydrochloric acid. The hydrochloric acid was removed by evaporation and the oily residue washed with ammonium hydroxide and water. The oil solidified and was recrystallized from aqueous ethanol. 15 g. of bis[3-(2- benzimidazolyl)propyl]disulphide were obtained.

(b) 21.5 g. of bis[3-(2-benzimidazolyl)propyl]disulphide dissolved in ml. of ethylene glycol monomethylether were reduced at a hydrogen pressure of 1500 p.s.i. using Re s as catalyst. The theoretical amount of hydrogen to be absorbed required about three hours of reduction. The catalyst was removed by filtration. The filtrate was concentrated by evaporation till dry. 20 g. of 2-(3- mercaptopropyl)benzimidazole were obtained.

(0) To a solution of 19.2 g. of 2-(3-mercaptopropyl) benzimidazole and 4 g. of sodium hydroxide in 200 ml. of methanol, 12.2 g. of propanesultone were added and the whole was refluxed for 2 hours under nitrogen atmosphere. The solution was filtered over decolourising carbon, the methanol removed by evaporation and the residue taken up in alkali. Then the solution was filtered and acidified whereupon the precipitate formed was recrystallized from water, yielding 16 g. of 2-[3-(3-sulphopropylthio)propyl1- benzimidazole.

Preparation 12:Compound 12 94 g. of 3,4-diaminobzenesulphonic acid and 84 g. of (phenylthio)acetic acid were refluxed for 12 hours in 2.6 litres of 6 N hydrochloric acid. The solution was filtered over decolourising carbon, the hydrochloric acid was removed by evaporation and the residue recrystallized from methanol. Yield: 69 g. of 2-phenylthiomethyl-5(6)-sulphobenzimidazole.

Preparation 13 :Compound 13 To a solution fo 54.8 g. of the disodium salt of 2- mercapto-S(6)-sulphobenzimidazole in 250 ml. of dimethyl formamide a solution of 25 g. of 2-chloroethylethioethane in 50 ml. of dimethyl formamide was added slowly with stirring. The temperature was kept between 80 and 90 C. for 3 hours. The sodium chloride formed was fil tered 01f and the dimethyl formamide was removed by evaporation. The brown solid formed was taken up in alkali, filtered over decolourising carbon and acidified. The precipitated product was recrystallized from water yielding 36 g. of 2-[2-(ethylthio)ethylthio]-5(6)-su1phobenzimidazole.

Preparation 14:Compound 14 9.4 g. of 3,4-diaminobenzenesulphonic acid and 6.5 .g. of tetrahydrothiophene-Z-carboxylic acid prepared by the method described by NJ. Putokhin and VS. Egorova in Zhur. Obshchai Khim. (J1. Gen. Chem.) 18, 1866 (1948) (C. A. 43, 3817 1949), were refluxed for 6 hours in 260 ml. of N hydrochloric acid. The solution was filtered over deoolourising carbon, the hydrochloric acid removed by evaporation and the residue recrystallised from methanol yielding 3 g. 2-(tetrahydro-Z-thienyl)-5(6)-sulphobenzimidazole.

Preparation l5zCompound (a) 56.5 g. of 3,4-diaminobenzoic acid hydrochloride and 35 g. of mercaptoacetic acid (80%) were refluxed for 12 hours with stirring in 420 m1. of 6 N hydrochloric acid. The precipitate formed on cooling was recrystallized from water yielding 59 g. of Z-mercaptomethyl-S(6)-carboxybenzimidiazole hydrochloride.

(b) To a mixture of 24 g. of 2-mercaptomethyl-5(6)- carboxybenzimidazole hydrochloride and 12 g. of sodium hydroxide in 300 m1. of methanol, 12.2 g. of propanesultone were added and the whole was refluxed for 3 hours with stirring. The methanol was removed by evaporation and the residue taken up in alkali. Then the solution was filtered over decolourising carbon and acidified whereupon the precipitate formed was recrystallized from water yielding 17 .g. of 2-(3-sulphopropylthiomethyl)-5(6)-carboxybenzimidazole.

Preparation 162Compound 16 To a solution of 17.8 g. of 2-o-mercaptophenyl-A lmidazoline prepared according to J1. Org. Chem. 1929, 52621 and 5.4 g. of sodium methylate in 200 ml. of methanol, 12.2 g. of propanesultone were added and the whole was refluxed for 2 hours. The methanol was removed by evaporation and the residue dissolved in 2 litres of water whereupon the solution was filtered over decolourising carbon and conducted over beads of insoluble sulphonated polystyrene as cation exchanger. The eluate was concentrated by evaporation and the residue recrystallized from ethanol/isopropanol yielding 5 g. of 2[o-(3-sulphopropylthio)phenyl]-A -imidazoline.

Preparation 171Compound 17 37.6 g. of 3,4-diaminobenzenesulphonic acid and 33.6 g. of o-(methylthio)benzoic acid were heated for 6 hours at 200 C. in 100 g. of polyphosphoric acid. After quenching with 500 ml. of water the solid was dissolved in alkali whereupon the solution was filtered over decolourishing carbon and acidified yielding 54 g. of Z-(o-methylthiophenyl) -5 (6) -sulphobenzimidazole.

Preparation 18 :Compound 18 20.6 g. of 3,4-diaminobenzenesulphonic acid and 7.5 g. of bis(carboxymethyl)sulphide were refluxed for 12 hours in 400 ml. of 6 N hydrochloric acid. The hydrochloric acid was removed by evaporation, the residue taken up in alkali and the solution formed filtered over decolourising carbon and acidified yielding 11 g. of bis(5(6)-sulpho-2- benzimidazolylrnethyl) sulphide.

Preparation 19:Compound 19 43.2 g. of disodium salt of 2-mercaptomethyl-5(6)-sulphobenzimidazole and 11.4 g. of allyl chloride were heated in 250 ml. of dimethyl formamide for 6 hours at 70 C. The dimethyl formamide was removed by evaporation-and the residue taken up in alkali whereupon the solution was filtered over decolourising carbon and acidified. The precipitate formed was recrystallized from water yielding 7 g. of 2-a.llylthiomethyl-5(6) sulphobenzimidazole.

Preparation 20:Compound 20 To a solution of 32.8 g. of Z-mercaptomethylbenzimidazole in 250 ml. of 1 N sodium hydroxide a solution of 8 47.2 g. of disodium a-bromosuccinate in ml. of water was added at 50 C. After having been stirred for 30 min. the solution was acidified with acetic acid and the precipitate formed recrystallized from water yielding 22 g. of 2-(a-succinylthiomethyl) benzimidazole monohydrate.

[Preparation 21 :Compound 21 206 g. of 3,4-diaminobenzenesulphonic acid and 21.5 g. of (phenylseleno)acetic acid prepared according to J1. Chem. Soc. 1928, 2293 were refluxed for 12 hours in 500 ml. of 6 N hydrochloric acid and 200 ml. of dioxan. The solution was filtered over decolourising carbon, the solvents removed by evaporation and the residue taken up in alkali. The solution was filtered and acidified whereupon the solid formed was filtered and recrystallized from water yielding 8 g. of Z-phenylselenomethyl-S (6)-sulphobenzimidazole.

Preparation 22:Compound 22 (a) 1-(methylthio)acetylthiosemicarbazide was prepared by the addition whilst stirring, of 124.5 g. of (methylthio)acetyl chloride to a suspension of 91 g. of thiosemicarbazide in 1 litre of dry pyridine. The temperature was maintained between -5 and 0 C. throughout the addition. The reaction mixture was left standing over night at room temperature whereupon most of the pyridine was removed by evaporation under reduced pressure.

In order to efliect cyclization to S-methylthiomethyllH-l,2,4-triazole-3-thiol the residue was dissolved in 1 litre of methanol and 108 g. of sodium methylate was added. The mixture was heated overnight on the steambath, and then the solvent was removed by evaporation under reduced pressure. The residue was dissolved in 2.5 litres of water and the solution formed was treated with decolourising carbon whereupon it was acidified with 300 ml. of hydrochloric acid. The precipitate was collected on a filter and recrystallized from ethanol yielding 68 g. of S-methylthiomethyl-lH-1,2,4-triazole-3-thio1.

(b) To a solution of 16.1 g. of S-methylthiomethyl-lI-I- 1,2,4-triaz0le-3-thiol in 200 ml. of methanol were added 12.2 g. of propanesultone. The whole was refluxed for 2 hours whereupon the solution was acidified with hydrochloric acid and the methanol removed by evaporation. The residue was crystallized from methanol. 12 g. of 3-(3- sulphopropylthio) S-methylthiomethyl-IH-1,2,4-triazole were obtained.

Preparation 231Compound 23 To a suspension of 3-(3-sulphopropylthio)-5-mercapto- 1H-l,2,4-triazole sodium salt in a solution of 4.29 g. of potassium in 450 ml. of ethanol, 14.9 g. of chloroethyl ethyl sulphide were added at room temperature. After having been refluxed for 4 hours the mixture had become neutral. It was cooled and the precipitate formed was filtered by suction. The product was dissolved in water and conducted over an ion exchanger. The solution was evaporated till dryness and the oil obtained was neutralized with potassium hydroxide. The solution was evaporated and the residue recrystallized from methanol. Yield: 10 g.

The compounds according to the present invention are generally incorporated into the silver halide emulsion layer of the light-sensitive material. The way in which the compounds of use according to the invention are added to emulsions is not critical and the addition can be made during no matter what step of emulsion preparation; they can be added before or after the emulsion has been optically sensitized, preferably just before coating of the emulsion on a suitable support such as for example paper, glass or film.

Instead of incorporating the compounds of the invention into the emulsion layer they can also be incorporated into another layer of the photographic material, e.g. a gelatin antistress layer or intermediate layer, which is in water-permeable relationship with the said emulsion layer or into one of the processing baths for said photographic material.

The antifoggants of use according to the present invention may be incorporated into any type of light-sensitive material comprising a silver halide emulsion layer e.g. a spectrally sensitized or non-sensitized silver halide emulsion layer, a silver halide emulsion layer of use in diffusion transfer processes for the production of silver images, an X-ray emulsion layer, and an emulsion layer sensitive to infra-red radiation. They may be incorporated into high speed negative materials as well as into rather low speed positive materials. Various silver salts may be used as light-sensitive salt e.g. silver bromide, silver iodide, silver chloride, or mixed silver halides e.g. silver chlorobromide of silver bromoiodide.

The silver halides are dispersed in the common hydrophilic colloids such as gelatin, casein, zein, polyvinyl alcohol, carboxymethylcellulose, alginic acid, etc., gelatin being, however, favoured.

The amount of antifoggant employed in the light-sensitive silver halide material depends on the particular type of emulsion and the desired eifect and can vary within very wide limits. The optimum amount of antifoggant to be added is best determined for each particular type of emulsion by trial. Generally, the most suitable concentration is between 0.2 millimole and 30 millimoles of antifoggant per mole of silver halide.

The light-sensitive emulsions may be chemically as well as optically sensitized. They may be chemically sensitized by effecting the ripening in the presence of small amounts of sulphur containing compounds such as allyl thiocyanate, allyl thiourea, sodium thiosulphate, etc. The emulsions may also be sensitized by means of reductors for instance tin compounds as described in our British patent specification 789,823 and small amounts of noble metal compounds such as of gold, platinum, palladium, iridium, ruthenium and rhodium.

Other addenda such as hardening agents, wetting agents, plasticizers, colour couplers, developing agents and optical sensitizers can be incorporated into the emulsion in the usual way.

The antifoggants according to the present invention are particularly suitable for use in conjunction with compounds which sensitize the emulsion by development acceleration for example alkylene oxide polymers. These alkylene oxide polymers may be of various types. Various derivatives of alkylene oxides may be used to sensitize the silver halide emulsions e.g. alkylene oxide condensation products as described among others in United States patent specifications 2,531,832 and 2,533,990, in United Kingdom patent specifications 920,637, 940,051, 945,340 and 991,608 and in Belgian patent pecification 648,710. Other compounds that sensitize the emulsion by development acceleration and that are suitable for use in combination with the antifoggants of use according to the invention are the onium derivatives of amino-N-oxides as described in United Kingdom patent specificaiton 1,121,- 696.

The stabilizers according to the invention can also be used in conjunction with other known stabilizers for instance with heterocyclic nitrogen containing thioxo compouds such as benzothiazoline-Z-thione and 1-phenyl-A tetrazoline-S-thione, with mercury compounds such as those described in Belgian patent specifications 524,121 and 677,337 and in Belgian patent specification 707,386 and 709,195 and preferably with compounds of the hydroxytriazolopyrimidine type (hydroxyazaindolizines), particularly in extreme storage and development circumstances.

In the following examples the stabilizing and fog-inhibiting action of the compounds corresponding to the above general formula is illustrated by incubation tests on photographic materials incorporating said compounds.

The values I and II given for the speed are exposure values corresponding with density 0.1 above fog and density 1 above fog respectively. A decrease of the value by 30 means a doubling of the speed.

EXAMPLE 1 A series of six identical conventional photographic gelatino silver bromoiodide emulsions (4.5 mole percent iodide) comprising an amount of silver halide equivalent to 50 g. of silver nitrate per kg. of emulsion was prepared. To each of these emulsions except for one, was added a compound as listed in the table below in a concentration of.'0.001 mole per kg. of emulsion. Then the emulsions were coated on a conventional support and dried.

The values of speed, gradation and fog of the materials formed were determined shortly after preparation and after incubation for 5 days at 57 C. and 35% relative humidity. The values obtained are listed in the table below.

Development occurred at 2 0 C. for 5 min. in a developing solution having the following composition:

Water8-00 ccs. p-Monomethylaminophenol sulphate-1.5 g.

Sodium sulphite (anhydrous)-50 g. Hydroquinone-6 g. Sodium carbonate (anhydrous)-32 g. Potassium bromide2 g. Water to make1000 ccs.

TABLE Fresh material Incubated material S eed S eed Compound Grada- Gradap a ded Fog tion 1 II Fog tion I II None 0.10 1.86 76 122 0.71 1.62 81 129 8 0.09 2.09 86 131 0.23 1.82 75 121 9. 0. 07 1.97 89 134 0.17 1.78 73 123 7. 0.10 1.90 84 129 0.29 1.69 71 120 1 0.09 1.98 79 127 0.25 1.50 61 119 1-methyl-2-(3- snlphopropylthiomethyDbenZ- lmidazole 0.07 1.95 78 123 0.43 1.55 67 11s This example proves clearly that compounds closely similar to those of the invention but having instead of the --NH-group in the heterocyclic ring an 1N(R)- group, R being a substituent, have a less good stabilizing effect.

EXAMPLE 2 Example 1 was repeated with the difference that the emulsion was divided into 10 aliquot portions to which the compounds listed in the table below were added in a concentration of 1 millimole per kg. of emulsion.

The following sensitometric results were attained.

Fresh material Incubated material S eed S eed Compound Grada- Gradaadded Fog tton I II Fog tion I II 1.75 35 121 0.31 1.74 73 113 3 2.10 91 123 0.13 1. s4 33 11s 2-methyl-5(6)- sulphobenaimidaZole 0.20 1.84 77 115 1.09 1.70 73 126 2-methylthiobenzimidazole 0.12 2.20 87 119 0.02 1.71 so 122 2-methylthiomethylbenZimidazole 0.15 2.16 96 127 1. 84 124 2-(2-methylthlo ethyDbenzimidaZole 0.13 2.09 98 133 1.39 117 166 2-methylthio5-(6)- sulphobenzimidazole 0.20 1.67 79 119 1.04 1.18 125 2carbozymeth lthiobenzimi aZ'ole 0.07 1.78 80 121 1.04 1.18 92 2-(3-sulphopropylthio)benzirnidazole 0.23 2.00 73 118 1.11 1.70 79 131 From this example it appears that compounds similar to compounds 2 and 3 but wherein the thio group is directly linked to the heterocyclic nucleus i.e. through the sulphur atom and/or no water-solubilizing group is present, having no stabilizing action.

EXAMPLE 3 Example 1 was repeated with the difierence that the emulsion was divided into seven aliquot portions to which the compounds listed in the table below were added in a concentration of 1 millimole per kg. of emulsion.

The following sensitometric results were attained.

Fresh material Ineubated material Speed Speed Compound Grada- Gradaadded Fog tion I II og tlon I II EXAMPLE 4 Example 1 was repeated with the difference that the emulsion was divided into 5 aliquot portions to which the compounds listed in the table below were added in the indicated concentration per kg. of emulsion.

The following sensitometric results were attained.

Example 1 was repeated with the difference that the emulsion was divided into 2 portions to which the compounds listed in the table below were added in the indicated concentration per kg. of emulsion.

The values of the fog produced in the stored materials as compared with the values of the fog produced in the freshly prepared materials are listed in the following table.

Fog 1n Fog in fresh stored Compound added materials materials None 0. 11 0. 89 1 rnmole of compound 23--- 0. 08 0. 17

What we claim is:

1. Photographic material comprising a support and at least one light-sensitive silver halide emulsion layer comprising in said emulsion layer and/or in at least one water-permeable layer coated at the same side of the support as the said emulsion layer at least one compound corresponding to the following general formula:

wherein:

Z represents the atoms necessary to complete a heterocycle;

Q stands for sulphur or selenium;

A stands for an alkylene group, an alkylene group interrupted by one or more hetero atoms, an S-alkylene group, an S-alkylene group interrupted by one or more hetero atoms, or an arylene group;

X stands for an alkyl group, an alkenyl group or an aryl group, or

A and X together represent the atoms necessary to complete a saturated heterocycle, and

wherein a -COOM or S0 M group, with M=hydrogen, ammonium, a metal atom, or an organic amine, is linked directly or indirectly to the grouping Z and/or X.

2. Photographic light-sensitive silver halide material according to claim 1, wherein said compound is present in the light-sensitive silver halide emulsion layer in an amount between 0.2 and 30 millimoles per mole of silver halide.

3. Photographic light-sensitive silver halide material according to claim 1, wherein said material also comprises a stabilizer of the hydroxytriazolopyrimidine type.

4. Photographic light-sensitive silver halide material according to claim 1, wherein said material also comprises a development accelerator of the polyoxyalkylene type.

5. Photographic light-sensitive silver halide material according to claim 1, wherein said emulsion layer is a gelatino silver halide emulsion layer.

6. Photographic light-sensitive silver halide material according to claim 1 wherein X and A together represent the atoms necessary to complete a saturated heterocycle.

7. Photographic light-sensitive silver halide material according to claim 1 wherein A stands for an alkylene group, an alkylene group interrupted by one or more hetero atoms, an S-alkylene group, an -S-alkylene group interrupted by one or more hetero atoms or an arylene group and X stands for an alkyl group, an alkenyl group or an aryl group.

References Cited UNITED STATES PATENTS 2,514,650 7/1950 Knot t et a1. 96-96 X 3,137,578 2/1962 De Selms 96109 X 3,305,362 2/1967 Riester et al. 96l06 X NORMAN G. TORCHIN, Primary Examiner I. L. GOODROW, Assistant Examiner US. Cl. X.R. 96-96 

